Palynostratigraphy and age correlation of subsurface strata within the sub-basins in Singrauli Gondwana Basin, India
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Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow, India. 2 Coal Wing, Geological Survey of India, Kolkata, India. ∗ Corresponding author. e-mail: bsip [email protected]
In the study area, changes in the facies of sediments and spores-pollen content appear to be all causally linked with the depositional set-up. Here, the qualitative and quantitative changes observed in the spores-pollen assemblages have led to recognize 10 Assemblage-zones representing from that earliest Permian in the Talchir Formation to that latest Late Triassic in the Parsora Formation. These sporespollen assemblages are obtained from the wider parts in the Singrauli Gondwana Basin that includes (i) Moher sub-basin (boreholes SSM-1 and 2), and (ii) Singrauli main sub-basin (boreholes SMJS-2, 3 and SMBS-1). The progressively changing spores-pollen content infer the hiatuses of varied magnitude in the sedimentary sequences during the extended time interval of Permian and Triassic.
1. Introduction The sedimentary sequences comprising the Permian and Triassic deposits in the Singrauli Gondwana Basin are intersected in number of borecores, and these deposits are widely scattered (figures 1, 2). Previous spores-pollen studies carried out in the subsurface deposits in this basin (Bharadwaj and Sinha 1969a,b; Sinha 1972; Tiwari and Srivastava 1984; Tripathi et al. 2005) have documented the existence of Upper Permian and Upper Triassic strata punctuated within many hiatus levels. Present study includes dating of subsurface strata in boreholes SMJS-2, 3, and SMBS-1, in the Singrauli main sub-basin. Beside this, the spores-pollen data from the Moher sub-basin (boreholes SSM-1 and 2 in Tripathi et al. 2005) has also been included herein to built-up the palynostratigraphy in the Singrauli Gondwana Basin. The spores-pollen studies done in these five borecores
are interpreted for age correlation of the sedimentary sequences from that earliest Permian through Late Triassic. 2. Geology The Singrauli Gondwana Basin (figures 1, 2) is the northernmost part of the Son-Mahanadi master Gondwana Basin, and is situated in the drainage area of Son and Rihand rivers. In the heart of peninsular India, it occupies the northwestern zone between NW–SE trending rift zone of Son/Mahanadi Valley Basin and east–west trending Tatapani–Koel–Damodar Basin. As the Gondwana sediments in Singrauli Gondwana Basin were deposited through fluvial network, it contains a predominance of sandstone dominated cycle. This character is typical of the Son Valley Basin belt (Mukhopadhyay and Mukhopadhyay 1999).
Keywords. Spores-pollen; Permian; Triassic; Singrauli Gondwana Basin; India. J. Earth Syst. Sci. 121, No. 4, August 2012, pp. 1071–1092 c Indian Academy of Sciences
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Figure 1. Map of Singrauli Gondwana Basin to show the Majhauli block, and the location of three borehols – SMJS-2, 3, and SMBS-1.
Figure 2. Part of Singrauli Gondwana Basin to show the Mahuli–Mahersop block, and the location of two boreholes SSM-1 and SSM-2.
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